Phthalate esters are used as plasticizers of resin products, such as polyvinyl chloride, which are used as cable covering material for example. The phthalate esters used as plasticizers are, di (2-ethylHexyl) phthalate (DEHP), dibutyl phthalate (DBP), butylbenzyl phthalate (BBP), diisononyl phthalate (DINP), and the like.
Of these phthalate esters, three phthalate esters DEHP, DBP, and BBP are listed as substances of very high concern (SVHC), in the regulation of REACH (registration, evaluation, authorisation and restriction of chemicals) in Europe. Also, these three substances are listed as regulation candidate substances in the directive of RoHS (Restrictions of the certain Hazardous Substances in electrical and electronic equipment) which restricts use of certain hazardous substances in electrical and electronic equipment.
There is a well-known technology that uses a spectrometric analysis method to analyze phthalate esters included in a product, such as cable covering material mentioned above, in a more time-efficient and cost-efficient manner than gas chromatography mass spectrometry and liquid chromatography mass spectrometry. For example, there is a conventional technology in which a specimen that has collected steam generated by heating cable covering material on a substrate is used to measure an IR spectrum of the specimen by Fourier transform-infrared spectroscopy (FT-IR) in order to determine presence or absence of phthalate esters.
See, for example, Japanese Laid-open Patent Publication No. 2012-154718
The conventional spectrometric analysis technology can determine presence or absence of phthalate esters from a measured spectrum. However, there is no significant difference between spectra of different phthalate esters. Hence, it is sometimes difficult to accurately identify the type of a phthalate ester from the measured spectrum, for example whether the phthalate ester is DEHP which is listed as a regulation candidate of the RoHS directive or DINP which is not listed as a regulation candidate.